Hemiphyllodactylus samkos, Neang & Samorn & Hun & Henson & Stuart, 2024

Neang, Thy, Samorn, Vireak, Hun, Seiha, Henson, Adam & Stuart, Bryan L., 2024, Review of the Slender Geckos (Squamata: Gekkonidae: Hemiphyllodactylus) of the Cardamom Mountains of southwestern Cambodia, with descriptions of two new species and one country record, Zootaxa 5537 (3), pp. 377-394 : 386-388

Hemiphyllodactylus samkos sp. nov.

Fig. 4

Hemiphyllodactylus cf. yunnanensis Grismer, Neang, Chav, Wood, Oaks, Holden, Grismer, Szutz & Youmans, 2008b:169 ; Grismer, Wood, Anuar, Muin, Quah, McGuire, Brown, Ngo & Pham, 2013:880; Grismer, Wood, Anuar, Quah, Muin, Chan, Sumarli & Loredo, 2015:876; Grismer, Wood, Thura, Zin, Quah, Murdoch, Grismer, Li, Kyaw & Lwin, 2017:915; Grismer, Wood, Zug, Thura, Grismer, Murdoch, Quah & Lin, 2018:316.

Hemiphyllodactylus sp. Neang, Hartmann, Hun, Souter & Furey, 2014:73.

Holotype. CBC 01693 (field tag NT 00815), adult female, Cambodia, Pursat Province, Veal Veng District, Phnom Dalai, Phnom Samkos Wildlife Sanctuary , 12.41392ºN, 103.10361ºE, 1,106 m elev., coll. 20 June 2011 by Thy Neang.

Paratype. CBC 01377 (field tag NT 00593), adult male, Cambodia, Pursat Province, Veal Veng District, Khnorng Tracheak, Phnom Samkos Wildlife Sanctuary , 12.15511ºN, 102.98882ºE, 1,290 m elev., coll. 14 December 2010 by Thy Neang .

Referred material. LSUHC 8242 , adult female, Cambodia, Pursat Province, Phnom Tumpor, Phnom Samkos Wildlife Sanctuary , 14.15790ºN, 103.48008ºE, 1,100 m elev., coll. 8 May 2006 by L. Lee Grismer, Thy Neang, et al .

Diagnosis. A bisexual species of Hemiphyllodactylus having the unique combination of maximum SVL 45.9 mm; chin scales eight; intersupranasal scales two; circumnasal scales four; supralabial scales 10–12; infralabial scales 9–10; dorsal scales within one diameter of eye 18; ventral scales 9–10; SubdigLam FI four; SubdigLam FII–V 4554; SubdigLam FTot 18; Subdig TI four; SubdigLam TII–V 4(5)555R/5665L; SubditLam TTot 19–22; PreCloFem Pores absent; and cloacal Spurs 2–3 on each side.

Description of holotype. Adult female, SVL 40.9 mm; head triangular in dorsal profile, distinct from neck, HL 10.3 mm, longer than wide, HW 6.7 mm, slightly depressed, HD 4.2 mm; rostrum relatively long, rounded in dorsal profile, SnEyeD 3.8 mm, 37% of HL; eye rounded, relatively moderate in size, EyeD 2.5 mm; ear oval, EarDH 0.9 mm, EarDV 0.8 mm; Eye-EarD 3.1 mm, slightly larger than ED. Rostral subrectangular with median notch dorsally, 1.9 mm in width, 0.9 mm high, in contact with first supralabials laterally, supranasals, intersupranasals dorsally; supranasals two, similar in size, separated by intersupranasals; intersupranasals two, much smaller than supranasals; circumnasal scales four; external nares in contact with rostral anteriorly, supralabials ventrally, supranasals dorsally, postnasals posteriorly; postnasal scales 2R/2L; lore oblique dorsally; canthus rostralis rounded, slightly depressed anteriorly; frontal region slightly concave; supralabials 12R/11L, subrectangular, first the largest, tapering posteriorly, 12 th / 11 th the smallest on right and left sides respectively; infralabials 9R/10L, subrectangular, tapering posteriorly, first the largest, 9 th and 10 th the smallest on right and left sides respectively.

Scales on top of head, lore, nuchal region small, rounded, granular, homogenous; scales on supraocular regions similar to those on rostrum, strongly granular, slightly larger than those on top of head; a row of slightly enlarged scales immediately bordering above supralabials; two rows of subimbricate superciliaries, relatively flat, squarish, subimbricate, largest anteriorly, smallest posteriorly; mental relatively small, triangular, 1.1 mm in width, 0.9 mm in length, in contact with infralabials laterally, two postmental scales posteriorly; postmentals two, distinctly enlarged, in contact with each other medially, mental anteriorly, enlarged scales laterally, gular scales posteriorly; chin scales eight, the two postmentals largest; gular scales immediately posterior to postmentals enlarged, larger than those granular on gular and anterior throat region; posterior throat flat, imbricate, similar to those on ventral scales.

Body small, elongated, depressed ventrally, TrunkL 20.4 mm, 50% of SVL; dorsal scales within one diameter of eye transversely across mid-dorsum 18, small, granular, lacking enlarged emerging tubercles; scales on upper flanks similar in size to those on dorsum, on lower flanks larger, slightly flat, subimbricate, grading into flat ventral scales; ventral scales within one diameter of eye 10, flat, smooth, imbricate; ventrolateral fold absent; enlarged precloacal scales 10; enlarged femoral scales absent; postcloacal spurs 3R/2L on lateral tail base; forelimb relatively short, bearing five fingers with strongly unsheathed curved claws, on tip of free terminal phalanx, except first finger vestigial, cone-shaped. Fingers II–V with expanded pads; enlarged subdigital lamellae wider than long, on Finger I 4R/4L; proximal subdigital lamellae on Fingers II–V undivided, angular, with U-shape distal subdigital lamellae divided, distal lamellae formula of Fingers II–V 4554 on each side, total lamellae on Fingers II–V 18; forearm and fingers with flat scales, subimbricate dorsally and ventrally; palmar with flat scales, subimbricate; hindlimb long, more robust than forelimb, with flat, dorsally juxtaposed, larger scales, those on anterior thigh larger than those on posterior thigh; scales on plantar region flat, subimbricate; hindlimb bearing five toes with unsheathed claws except Toe I vestigial, cone-shaped, distal portion of toes strongly curved, terminal joint free; enlarged subdigital lamellae on Toe I 4R/4L; proximal subdigital lamellae on Toes II–V undivided, angular, with U-shape distal subdigital lamellae divided, distal lamellae formula of Toes II–V 4555R/5555L, total lamellae on Toes II–V 19R/20L; tail short, TaL 17.4 mm, regenerated, depressed, tapering posteriorly; dorsal caudal scales small, flat anteriorly, larger posteriorly; caudal scales small anteriorly, larger posteriorly, slightly larger than lateral and dorsal caudal scales ( Table 1).

Coloration of holotype in life. Ground color of head, body, flanks and limbs light brown to gray with dark and greyish irregularly shaped markings; grey color arranged mostly as transverse crossbars; rostrum dark brown with scattered light brown markings; light tan-brown stripe begins posterior to supranasals, extends along canthus rostralis above eye to level of above tympanum; larger dark brown stripe bordered below the light tan brown begins from postnasals along loreal through eye, above tympanum to forelimb insertion; rostral, supralabials and infralabials dark brown; dorsal surface of limbs with dark brown markings; tail regenerated, light brown anteriorly, dark brown posteriorly; irregular dark brown postsacral marking bordered posteriorly by white scales.

Coloration of holotype in preservative. Dark brown markings faded, greyish markings faded to whitish; dorsal surface of head, body, flanks, and limbs purely light brown with small dark brown spots on scales and between scales; chin whitish; throat, ventral surfaces of body, limbs and tail whitish with tiny dark stippling on scales, except anterior section of regenerated fragment on tail distinctly brown.

Variation. Morphometric and meristic characters of the type series are presented in Table 1. The paratype has a subdigital lamellar formula on Toes II–V 5665 (vs. 4555R/5555L in the holotype), ventral scales within one diameter of eye nine (vs. 10 in holotype), and enlarged precloacal scales 11 (vs. 10 in holotype).

Distribution and natural history. The new species is currently known only from 1,106 –1,290 m elevation at Phnom Samkos Wildlife Sanctuary in Veal Veng District, Pursat Province, Cambodia. The holotype was found during the day under a rotten log in primary forest ( Fig. 4 ). The paratype dropped during the day from a tree branch approximately 15 m above the ground in submontane forest and landed on the foot of a local guide accompanying the collector.

Etymology. The specific epithet is an invariable noun in apposition in reference to the type locality in Phnom Samkos Wildlife Sanctuary, Pursat Province, Cambodia. The suggested common name is Samkos Slender Gecko (English).

Comparisons. Hemiphyllodactylus samkos sp. nov. is phylogenetically related to other species from the southern Indochinese peninsula, specifically H. indosobrinus from southern Laos, H. bokor sp. nov., H. flaviventris from eastern Thailand, and H. cattien and H. dalatensis from southern Vietnam, as well as a clade of six species from India, specifically H. arakuensis , H. aurantiacus , H. goaensis , H. jnana , H. kolliensis , and H. minimus .

Hemiphyllodactylus samkos sp. nov. is the sister taxon to H. flaviventris from eastern Thailand, but differs by having larger body size, with maximum SVL 45.9 mm (vs. 39.2 mm in H. flaviventris ), circumnasals four (vs. five in H. flaviventris ), subdigital lamellae on Fingers II–V 4554 (vs. 4444 in H. flaviventris ), subdigital lamellae on Toes II–V 4(5)555R/5665L (vs. 4555 in H. flaviventris ), lamellae on Finger I four (vs. five in H. flaviventris ), lamellae on Toe I four (vs. five in H. flaviventris ), and precloacal and femoral pores absent [vs. present (19–20) in H. flaviventris ].

Hemiphyllodactylus samkos sp. nov. differs from H. bokor sp. nov. by having larger body size, with maximum SVL 45.9 mm (vs. 39.0 mm in H. bokor sp. nov.), circumnasals four (vs. five in H. bokor sp. nov.), intersupranasals two (vs. three in H. bokor sp. nov.), ventral scales within one diameter of eye 9–10 (vs. 15–16 in H. bokor sp. nov.), and lacking precloacal and femoral pores [vs. present (15) in H. bokor sp. nov.].

Hemiphyllodactylus samkos sp. nov. differs from H. indosobrinus by having circumnasals four (vs. three in H. indosobrinus ), intersupranasals two (vs. three in H. indosobrinus ), supralabials 10–12 (vs. 15 in H. indosobrinus ), infralabials 9–10 (vs. 12 in H. indosobrinus ), dorsal scales within one diameter of eye 18 (vs. 30 in H. indosobrinus ), subdigital lamellae on Toe I four (vs. five in H. indosobrinus ), lacking precloacal and femoral pores [vs. present (18) in H. indosobrinus ], and precloacal spurs on each side of tail base 2–3 (vs. one in H. indosobrinus ).

Hemiphyllodactylus samkos sp. nov. differs from H. cattien by having larger body size, with maximum SVL 45.9 mm (vs. 35.1 mm in H. cattien ), chin scales eight (vs. seven in H. cattien ), circumnasals four (vs. five in H. cattien ), intersupranasals two (vs. three in H. cattien ), dorsal scales within one diameter of eye 18 (vs. 20 in H. cattien ), subdigital lamellae on Fingers II–V 4554 (vs. 4444 in H. cattien ), subdigital lamellae on Finger I four (vs. five in H. cattien ), subdigital lamellae on Toe I four (vs. six in H. cattien ), lacking precloacal and femoral pores [vs. present (19) in H. cattien ], and precloacal spurs on each side of tail base 2–3 (vs. one in H. cattien ).

Hemiphyllodactylus samkos sp. nov. differs from H. dalatensis by having circumnasals four (vs. three in H. dalatensis ), dorsal scales within one eye 18 (vs. 16 in H. dalatensis ), and lacking precloacal and femoral pores [vs. present (23–25) in H. dalatensis ].

Hemiphyllodactylus samkos sp. nov. readily differs from its six Indian relatives H. arakuensis , H. aurantiacus , H. goaensis , H. jnana , H. kolliensis , and H. minimus by having SubdigLam FII–V 4554 (vs. 2222 in H. arakuensis , 2222 in H. aurantiacus , 2222 in H. goaensis , 2222 in H. jnana , 2222 in H. kolliensis , and 2222 in H. minimus ); SubdigLam FTot 18 (vs. eight in all six Indian species); SubdigLam TII–V 4(5)555R/5665L (vs. 2(3) 333 in H. arakuensis , 2(3)2(3) 33 in H. aurantiacus , 232(3) 3 in H. goaensis , 2222 in H. jnana , 2222 in H. kolliensis , and 2332(3) in H. minimus ); SubdigLam TTot 19–22 (vs. 11–12 in H. arakuensis , 9–12 in H. aurantiacus , 10–11 in H. goaensis , eight in H. jnana , eight in H. kolliensis , and 10–11 in H. minimus ); and lacking precloacal and femoral pores (vs. present in all six Indian species).

Although not phylogenetically closely related to H. yunnanensis ( Fig. 2 ), populations from the Cardamom Mountains have been previously referred in the literature to that species (e.g., Zug 2010). Hemiphyllodactylus samkos sp. nov. differs from H. yunnanensis by having smaller body size, maximum SVL 45.9 mm (vs. 49.3 mm in H. yunnanensis ), circumnasal scales four (vs. 2–4 in H. yunnanensis ), ventral scales 9–10 (vs. 6–12 in H. yunnanensis ), SubdigLam FII–V 4554 (vs. 3333 in H. yunnanensis ), and SubdigLam TII–V 4555–5665 (vs. 3444 in H. yunnanensis ).

Figures

FIGURE 2. Fifty percent majority-rule consensus phylogram resulting from partitioned Bayesian analysis of 1,042 characters of the coding region of the mitochondrial ND2 gene from Hemiphyllodactylus geckos and the outgroups Lepidodactylus lugubris, Dixonius siamensis, and Gehyra pilbara (not shown). Numbers at nodes are Bayesian posterior probabilities (left) and bootstrap values ≥ 50 from a separate maximum likelihood analysis (right). Species names are followed by GenBank accession numbers in parentheses. Illustrated from top to bottom (not to scale) are photographs in life of the holotype of Hemiphyllodactylus bokor sp. nov. (NCSM 98991), the holotype of Hemiphyllodactylus samkos sp. nov. (CBC 01693), and Hemiphyllodactylus typus (CBC 03120).

FIGURE 4. Holotype of Hemiphyllodactylus samkos sp. nov. (CBC 01693) in life (A) and in preservative with views of dorsum (B), venter (C), subdigital lamellae of hands (D), and subdigital lamellae of left foot (E). Habitat at the type locality of Hemiphyllodactylus samkos sp. nov. at Phnom Samkos Wildlife Sanctuary, Veal Veng District, Pursat Province, Cambodia (F).